The sorting of mailpieces is normally carried out as a function of sorting codes in which the address of the mailpieces is encoded. The sorting code is applied onto the mailpieces in machine-readable form, for example, as a barcode, after the delivery address has been detected. Once the mailpiece reaches a sorting machine, the sorting code is detected and the mailpiece is diverted into a sorting compartment associated with that sorting code.
In the postal code system normally used in Germany, the sorting code has, for example, eleven digits, whereby the first five digits correspond to the postal code contained in the delivery address, designating a so-called delivery district group comprising several delivery districts which, in turn contain the street sections within a town that are serviced by a single mail carrier. The next three digits contain encoded information about the street designation contained in the delivery address, whereby it can be provided, for example, that the street sections of a delivery district group are consecutively numbered in a prescribed manner. The last three digits of the sorting code correspond to the last three digits of the house number indicated in the delivery address.
The sorting of mailpieces is normally carried out in a method having at least two stages. First of all, the mailpieces dropped off in a given region are collected in a distribution center of a postal service provider associated with this region and, within the scope of the outgoing sorting, they are especially distributed among the distribution centers in the destination regions of the mailpieces. In these distribution centers, within the scope of the so-called incoming sorting, a fine sorting of the mailpieces is carried out during which they are distributed among the individual delivery districts in the destination region. Normally, the incoming sorting also comprises a sorting of the mailpieces according to the sequence in which the mail carriers provide service to the delivery points of the delivery districts.
In order to carry out the sorting as efficiently as possible and to prepare the incoming sorting, it is normally provided that the sorting depth during the outgoing sorting, that is to say, the number of digits of the sorting code that are relevant for the sorting, sometimes goes beyond the postal code or the first five digits of the sorting code. In this manner, for example, mailpieces for certain street sections of a delivery district or of a delivery district group can already be combined during the incoming sorting, said mailpieces being sorted during the incoming sorting in a machine inlet according to the sequence of the delivery route, or else mailpieces for a subrange of a delivery district or of a delivery district group can be diverted into a sorting compartment together with mailpieces for another delivery district group, in order to utilize the capacity of the sorting machine as effectively as possible. However, at times, the sorting is merely carried out according to the postal code or according to the first five digits of the sorting code.
The association of the sorting codes with the sorting compartments of a sorting machine is normally carried out on the basis of a so-called sorting plan that is read out by the sorting machines. On the basis of the structure of the sorting explained above, the sorting plans according to the state of the art normally comprise two lists, one of which contains the associations between postal codes or the first five digits of the sorting code and sorting compartments and is relevant for the sorting of the mailpieces for which only a sorting depth corresponding to the postal code is provided. The second list comprises the associations between complete sorting codes or intervals of complete sorting codes and sorting compartments for the sorting of mailpieces for which a sorting depth corresponding to the complete sorting code is provided.
In order to determine the sorting compartment for a mailpiece with a prescribed sorting code, the list that comprises the postal codes has to be checked so that it can be ascertained whether the first five digits of the prescribed sorting code correspond to one of the postal codes in the list. Furthermore, the list containing the complete sorting codes likewise has to be searched in order to check whether here, too, the prescribed sorting code corresponds to a sorting code contained in the list.
This has the drawback that the list of the postal codes as well as the list with the complete sorting codes have to be searched in order to determine the sorting compartment into which a mailpiece with a prescribed sorting code has to be diverted, which is very complicated and thus very time-consuming.